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Manifold Advice


Guest shadetree77

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Guest shadetree77

I recently removed the exhaust/intake manifolds from my '52. I need to take them apart in order to clean, repaint, and install new gaskets. I ran into my first problem already. The bolts appear to be a size between 9/16 and 1/2. Must be 17/32. Have to try and find a 17/32 socket and wrench somewhere. Looks like I'm going to have to order them from Grainger. Anyway, does anyone have any advice on taking these apart? The use of copious amounts of penetrating oil and heat are a given. Should I try to remove bolts by hand or with an impact? Any advice or experiences on the matter would be much appreciated.

Edited by shadetree77 (see edit history)
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The bolts are rusted to a smaller size. Very common on old rusted manifolds Sometimes a metric socket will work. The bolt size should be 3/8ths. The hex head, 9/16ths. Bolts are measured by the shank size. Replace the bolts with new ones. I have had nuts rusted so bad on old manifolds, (Not just old Buicks) that I have had to cut the nuts off. Do it by hand. Using an impact may just snap them off. Dandy Dave!

Edited by Dandy Dave (see edit history)
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I have very carefully marked and punched the center of a bolthead so I could start drilling with my smallest drill bit. By increasing the the bits in one or two increments you can remove it without damage to the thread. Sometimes the action of the drilling with set up vibrations that might loosen the threads. Somewhere in the garage I have a bolt with the center drilled out that way and it looks like a little piece of pipe. Lots of oil, accuracy, and a ton of patience gets it.

Be careful with the replacement bolt. Manufacturers did not always use hardware store length bolts. If you have to, cut a store bought bolt exactly to the length of the original. I had to heli-coil a '59 Cadillac block because of that one time. But that's another story.

Bernie

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Robert,

Unless the gasket between them is leaking, I wouldn't take them apart.

Like the head of the bolt, as Dandy Dave mentions, the threads in the bolt holes can also deteriorate and get smaller, making them easy to strip out when reinstalling everything. I guess that's why they make heli-coils, so the problems can be overcome, but you are asking for a lot of problems by taking the manifolds apart.

Pete Phillips, BCA #7338

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Guest shadetree77

Pete, trust me, I do not want to take them apart but I don't see any way around it. For one, the gasket between the exhaust manifold and the valve body is completely crumbled leaving big gaps between the two parts. Secondly, the service manual lays out a very specific tightening sequence for re-installing the manifolds which requires that all bolts be loose to begin with. I am well aware that I may be opening a veritable can of worms here but I just don't see any way around it if I want to do it right. I do have a sinking feeling in the pit of my stomach about the whole thing though. If something were to happen to those manifolds it would cause a serious set back in my efforts.

I was thinking about something today, I am planning to soak the manifolds in a rust removing solution. Should I go ahead and soak the ENTIRE assembly as it sits before trying to remove the bolts? Wouldn't the solution soak into the threads of the bolts and dissolve the rust thereby making them easier to remove? Let me know if my logic is flawed on this.

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Guest Hector

Worst case scenario you will shear all the bolts and will have to chase or repair the threads.I would try the lubricant and heat with a six point socket/breaker bar set up.If I can't get a good bite with the socket I may consider grinding the hex heads off the bolts in order to save some of the bolt to get a good set of visegrips and try to unscrew them,after the manifolds are separated.

I have dealt with quite a few exhaust manifolds in the past as far as reconditioning,patience really pays off.Most times I would prefer to just shear off the boltheads than having them break flush(then you have to be quite accurate with the drill).There is always helicoils to correct any unusable threads if it gets to that point.Good luck with it.

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Your logic is flawed. Cast iron, steel, rust, metallurgy, and 60 years of the Earth's magnetic flux are all against you. It would be a mechanical job if the bolts would turn, or a metallurgic job if heat would work. Experience rules those out. You have an archeological dig for threads on your hands. The last thing you want to do is break the manifold.

Once I had to put a gasket between the intake and exhaust on a Pierce-Arrow straight 8. The owner had so many tips and procedures he had gleaned from everybody and their brother I had to wait until he went to Florida on vacation to do the job right, err... ummmm..... my way.

Bernie

I looked around the garage for that bolt that looks like a threaded pipe yesterday, but I didn't surface. Time for you to make a couple.

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Your logic is flawed. Cast iron, steel, rust, metallurgy, and 60 years of the Earth's magnetic flux are all against you. It would be a mechanical job if the bolts would turn, or a metallurgic job if heat would work. Experience rules those out. You have an archeological dig for threads on your hands. The last thing you want to do is break the manifold.

Once I had to put a gasket between the intake and exhaust on a Pierce-Arrow straight 8. The owner had so many tips and procedures he had gleaned from everybody and their brother I had to wait until he went to Florida on vacation to do the job right, err... ummmm..... my way.

Bernie

I looked around the garage for that bolt that looks like a threaded pipe yesterday, but I didn't surface. Time for you to make a couple.

Been there, Done that. So many times I ran out of Fingers and Toes...Ahhh, bolts and customers both. :P Bernie, Automatic $10 an hour more for customers that want to give advice. :cool: Dandy Dave!

Edited by Dandy Dave (see edit history)
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